Err, I'd be very careful about raving about coming off IBS medications due to exercise. If you have diarrhoea predominant IBS, you can be halfway through a walk or run and feel like you're about to poop your pants, if you don't have medications.

Yes, there is an endorphin release from exercising, and I don't dispute that an one person's experience with antidepressants may not be another person's.